Counterflow leak-detector unit with a high-vacuum pump

Abstract

A counterflow leak-detector unit (1) with an inlet (2) connected to a test specimen, or a chamber housing a test specimen. A high-vacuum pump (4) produces pressure in a test-gas detector. The inlet (2) to the leak-detector unit is connected to an intermediate line (16) in the high-vacuum pump (4). To increase detection sensitivity without any danger of the pressure in the detector rising to inadmissible levels, a constriction (17) is located between two high-vacuum pump states (5, 6) of the high vacuum pump (4). Pump stages (5, 6) are separated by the intermediate line (16). The inlet (2) to the leak-detector unit (1) is connected to the outlet side of the high-vacuum pump state (5) at a point upstream of the constriction (17).

What is claimed is: 
     
       1. A countertflow leak-detector that includes a gas detector for detecting the presence of a specimen;   a multistage high vacuum pump having an upper pump stage connected to the gas detector for bringing the pressure in said gas detector to a predetermined level and a second lower pump stage connected to the upper pump stage by an intermediate flow line, said pump stages each having an inlet side and an outlet side;   a constriction in said intermediate flow line;   a means for containing a specimen; and   a connecting means for coupling said intermediate flow line and said means for containing a specimen, for introducing a specimen into said intermediate flow line.   
     
     
       2. The counterflow leak-detector according to claim 1, wherein said connecting means enters said intermediate flow line between said constriction and said upper pump stage. 
     
     
       3. The counterflow leak-detector according to claim 1, wherein said connecting means enters said intermediate flow line between said constriction and said lower pump stage. 
     
     
       4. The counterflow leak-detector according to claim 1, further comprising a common supply line (11) having a valve (12), operatively connected therein, said common supply line mounted between said outlet side of said lower pump stage and said means for containing a specimen. 
     
     
       5. The counterflow leak-detector according to claim 4, further comprising a lower line (7) having lower valve (8) and forevacuum pump (9), said forevacuum pump located on said outlet side of said lower pump stage, said common supply line connecting into said lower line between said lower valve and said forevacuum pump. 
     
     
       6. The counterflow leak-detector according to claim 1, wherein said constriction further comprises a means fur maintaining the conductance constant. 
     
     
       7. The counterflow leak-detector according to claim 6, wherein said means for maintaining the conductance includes a fixed ring disc (22), and said high-vacuum pump is a dual-stage drag pump. 
     
     
       8. The counterflow leak-detector according to claim 1, wherein said constriction further includes a means for controlling the conductance. 
     
     
       9. The counterflow leak-detector according to claim 8, wherein said means for controlling the conductance includes a ring disc (22) having adjustable components (26), and said high-vacuum pump is a dual-stage drag pump. 
     
     
       10. The counterflow leak-detector according to claim 9, wherein said components are made of materials having a shape memory effect capable of adjusting said constriction. 
     
     
       11. The counterflow leak-detector according to claim 1, wherein said upper pump stage and said lower pump stage are formed by two separate drag pumps. 
     
     
       12. The counterflow leak-detector according to claim 1, wherein said upper pump stage and said lower pump stage each having a separate rotor mounted on a common shaft (21). 
     
     
       13. The counterflow leak-detector according to claim 1, wherein said upper pump stage is a turbomolecular pump and said lower pump stage is a drag pump. 
     
     
       14. The counterflow leak-detector according to claim 1, wherein said upper pump stage is a turbomolecular pump with a relatively low compression for light gases and dimensioned such that it will generate on the pressure side a pressure of approximately 0.1 mbar or less, and wherein said lower pump stage is a screw-type pump having a relatively high pumping speed and dimensioned to produce on its outlet side a pressure of over 0.1 mbar, preferably 1 mbar. 
     
     
       15. The counterflow leak-detector according to claim 1, wherein said upper pump stage further contains two sections (5a, 5b). 
     
     
       16. The counterflow-leak detector according to claim 15, wherein said intermediate flow line is located between said two sections.